1. Department of Criminal Justice and Criminology
The Legalization of Marijuana and Resultant Marijuana-Related Arrest Rates Disaggregated by Race, Gender, and Age
Mikala Meize, MA
Department of Criminal Justice and Criminology
Research Team
Dale Willits, David Makin, Duane Stanton, Nicholas P. Lovrich, Craig Hemmens, Mary K. Stohr, John Snyder, Rachael Brooks, and multiple undergraduate students

2. Initiative 502 (Washington) & Amendment 64 (Colorado)
7/29/2019
What are I-502 and A-64?
Initiative 502 (Washington) & Amendment 64 (Colorado)
Ballot measures that legalized the use and sale of recreational marijuana
Passed in November 2012, implementation began in December 2012
Still illegal to:
Sell marijuana without retail license, possess marijuana under the age of 21, use marijuana in a public space, drive under the influence of marijuana, and possess marijuana over legal limits
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3. System-wide racial disparities (Beckett et al., 2005; Firth, 2018)
7/29/2019
Literature Review
System-wide racial disparities (Beckett et al., 2005; Firth, 2018)
Reallocation of police resources (Trilling, 2016)
Low priority offenses already (Ross &Walker, 2016)
Clearance rates for more serious offenses (Makin et al., 2018)
Black market changes (Richter & Levy, 2014)
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4. 7/29/2019
Aim
To determine the effects of the legalization of recreational marijuana on marijuana-related arrests across different demographic groups using an interrupted time-series analysis
Hypotheses
Overall arrest rates for possession should decrease in 2012, and arrest rates for sales should decrease over time
Arrest rates in general should decline post-legalization for all individuals except juveniles
Arrest rates across races should decrease similarly in 2012 and remain stable over time
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5. Uniform Crime Reporting (UCR) Program Data: 2009-2016
7/29/2019
Data
Uniform Crime Reporting (UCR) Program Data:
Only agencies that reported for all 12 months of each of the 8 years
124 agencies from Washington
60 agencies from Colorado
Census data for demographic information
Aggregated to state level
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6. Interrupted time-series analysis
7/29/2019
Methods
Interrupted time-series analysis
Population level changes with clear introduction of intervention
Routine measurements
Pre-intervention, immediately post-intervention, over time post-intervention compared to pre-intervention trends
Controlled for monthly autocorrelations
Monthly rates per 100,000 people
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7. Arrest Totals Washington Colorado Year Sales Possession 2009 931 5388
7/29/2019
Arrest Totals
Washington
Colorado
Year
Sales
Possession
2009
931
5388
440
6453
2010
1043
5065
435
6139
2011
771
5088
415
5800
2012
474
4292
379
5356
2013
242
1546
254
3187
2014
162
1347
323
3780
2015
160
1085
271
3781
2016
141
1168
364
3141
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8. Overall Possession Arrest Rate
7/29/2019
Overall Possession Arrest Rate
Pre-legalization: Significant decrease
Post-legalization : Significantly negative
Over time: Significantly positive
Pre-legalization: Significant decrease
Post-legalization : Significantly negative
Over time: Significantly positive
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9. Overall Sales Arrest Rate
7/29/2019
Overall Sales Arrest Rate
Pre-legalization: Significant decrease
Post-legalization : Significantly negative
Over time: Significantly positive
Pre-legalization: Significant decrease
Post-legalization : Significantly negative
Over time: Significantly positive
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10. WA Possession Arrests by Race
7/29/2019
WA Possession Arrests by Race
Pre-legalization: Significant decrease
Post-legalization : Significantly negative
Over time: No significance
Pre-legalization: Significant decrease
Post-legalization : Significantly negative
Over time: Significantly positive
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11. CO Possession Arrests by Race
7/29/2019
CO Possession Arrests by Race
Pre-legalization: Significant decrease
Post-legalization : Significantly negative
Over time: Significantly positive
Pre-legalization decrease, no statistically significant changes post-legalization or over time
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12. WA Sales Arrests by Gender
7/29/2019
WA Sales Arrests by Gender
Pre-legalization: Significant decrease
Post-legalization : Significantly negative
Over time: Significantly positive
Pre-legalization: Significant decrease
Post-legalization : No significance
Over time: Significantly positive
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13. CO Sales Arrests by Gender
7/29/2019
CO Sales Arrests by Gender
Pre-legalization: Significant decrease
Post-legalization : Significantly negative
Over time: Significantly positive
Pre-legalization: No significance
Post-legalization : No significance
Over time: Significantly positive
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14. WA Possession Arrests by Age
7/29/2019
WA Possession Arrests by Age
Pre-legalization: Significant decrease
Post-legalization : Significantly negative
Over time: No significance
Pre-legalization: Significant decrease
Post-legalization : Significantly negative
Over time: Significantly positive
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15. CO Possession Arrests by Age
7/29/2019
CO Possession Arrests by Age
Pre-legalization: Significant decrease
Post-legalization : Significantly negative
Over time: Significantly positive
Pre-legalization decrease, no statistically significant changes post-legalization or over time
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16. Prior to legalization decreases in arrest rates
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Discussion
Changes in arrest rates are not uniform across states, nor demographic groups
Prior to legalization decreases in arrest rates
Arrest rates for sales inconsistent with hypothesis
Arrest rates for juveniles inconsistent with hypothesis
Further evidence of shift in police priority/resources
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17. Limitations and Further Research
7/29/2019
Limitations and Further Research
State level versus agency level
Limited number of agencies
Time-series imputation
Time of first retail locations not included
Short-term trends
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18. 7/29/2019
Contact Information
Mikala Meize, M.A.
Dale Willits, Ph.D.
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